title: Mechanical spectroscopy and relaxometry on alginate hydrogels: a comparative analysis for structural characterization and network mesh size determination.
abstract: The structure of calcium-saturated alginate hydrogels has been studied by combining rheological determinations and relaxometry measurements. The mechanical spectroscopy analyses performed on alginate gel cylinders at different polysaccharide concentration allowed estimating their main structural features such as the average mesh size. The calculation was based on the introduction of a front factor in the classical rubber elasticity approach which was correlated to the average length of the Guluronic acid blocks along the polysaccharide chain. Transverse relaxation time (T(2)) determinations performed on the cylinders revealed the presence of two relaxation rates of the water entrapped within the hydrogel network. The cross-correlation of the latter data with the rheological measurements allowed estimating the mesh size distribution of the hydrogel network. The results obtained for the hydrogel cylinders were found to be consistent with the relaxometric analysis performed on the alginate microbeads where, however, only one type of water bound into the network structure was detected. A good correlation was found in the average mesh size determined by means of relaxometric measurements on alginate microbeads and by a statistical analysis performed on TEM micrographs. Finally, the addition of a solution containing calcium ions allowed investigating further the different water relaxation modes within alginate hydrogels.
authors.affiliation: Department of Life Sciences, University of Trieste, Via Licio Giorgieri 1, 34127 Trieste, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Turco
authors.forename: Ivan
authors.initials: I
authors.lastname: Donati
authors.forename: Mario
authors.initials: M
authors.lastname: Grassi
authors.forename: Giulia
authors.initials: G
authors.lastname: Marchioli
authors.forename: Romano
authors.initials: R
authors.lastname: Lapasin
authors.forename: Sergio
authors.initials: S
authors.lastname: Paoletti
mesh_terms: D000464:Alginates / Q000737:chemistry*; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D020100:Hydrogels; D009682:Magnetic Resonance Spectroscopy; D046529:Microscopy, Electron, Transmission
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D020100:Hydrogels; D020723:Glucuronic Acid